1. Field of the Invention
The present invention relates to the equipment employed for the performance of an angioplasty in a coronary artery or a peripheral artery.
2. Description of the Prior Art
An operation of this type is at present performed by making use of a catheter fitted on a flexible guide rod and adapted to carry at the distal end a dilation bulb which can be inflated by means of a duct provided for this purpose within the catheter. By means of the guide rod, it is possible to place the inflatable bulb at the precise point at which a dilation is to be carried out for the purpose of flattening atheromatous plates in order to restore a sufficient passage for the flow of blood. However, the disadvantage of this technique lies in the fact that, throughout the period of inflation of the dilation bulb, the blood flow is completely interrupted within the corresponding artery. In the case of a coronary artery, this may cause ischemia of the cardiac muscles, which is liable to give rise to various harmful or dangerous phenomena such as electrical modifications, chest pains, anomalies of left ventricular contractility. Furthermore, this may lead to arythmias which are liable to endanger the life of the patient.
It is for this reason that angioplasties can be performed only during a relatively short period of time of the order of 1 to 3 minutes. Under these conditions, an angioplasty must be repeated several times, thus exposing the patient to the risks mentioned above. Moreover, angioplasties present a restenosis rate of the order of 30% at six months, thus entailing the need to carry out further dilation operations. However, it is apparent from medical publications in this field that the restenosis rate is inversely proportional to the duration of the angioplasty which has been performed.
It is therefore necessary to develop techniques which make it possible to increase the time of inflation of standard dilation bulbs. To this end, it has already been proposed to carry out a perfusion of blood or of an oxygen-transporting physiological liquid downstream of the dilation bulb by employing the catheter itself as a perfusion tube. This makes it necessary to remove the guide rod after positioning of the bulb in order to free the internal space of the catheter. However, this perfusion technique as performed in a continuous mode has not made it possible to obtain fully satisfactory results and extension of the duration of an angioplasty therefore remains very limited.